Barracuda not starting after being parked for five years

phf said
Unfortunately, I don't have a spark tester. I held the number 1 wire with the plug in it on the exhaust manifold while my wife cranked the engine. No spark was visible.

That's fine. I thought you were working alone since you mentioned waiting 'til your wife was available to help.

AJ/FormS said
Hold on, I made the assumption that the ballast was ok.

You were correct to make that assumption. Phf measured voltage at the coil when the ignition is in run. It shows a drop, and thats to be expected.
There is a possibility that the ignition 2 wire is not connected so during start power isn't gettin gto the coil even though during run it is.
Phf, place the voltmeter so you can see it while turning the key to start (or ask your wife to help again). The coil should get battery voltage.

If its the original '67 harness, there's a brown wire to the ballast resistor from the ignition switch start position.
Its crimped onto the same connector as the blue wire leading to the coil.